var banner = new Array();

banner[0]='https://i.servimg.com/u/f11/12/30/07/53/00710.jpg';
banner[1]='https://i.servimg.com/u/f11/12/30/07/53/00810.jpg';
banner[2]='https://i.servimg.com/u/f11/12/30/07/53/00910.jpg';
banner[3]='https://i.servimg.com/u/f11/12/30/07/53/01010.jpg';

document.getElementById('i_logo').src= banner[Math.floor(Math.random()*banner.length)];